Read the book "A History of the world in 6 Glasses" by Tom Standage.
Watch the documentary by National Geographic "Guns, Germs, and Steel" the 3 part series is available for streaming on YouTube
Venture onto Khan Academy just for fun! Re-visit a topic you struggled with and watch some videos or try the practice assignments. With no pressure of a grade and a due date, you can use all the "hints" you want! Master factoring quadratics, graphing linear functions, or finally figure out what logarithms are all about! The possibilities are infinite!